U.S. patent application number 17/316614 was filed with the patent office on 2021-08-26 for hybrid copolymer composition for protecting foldable displays.
The applicant listed for this patent is Tactus Technology, Inc.. Invention is credited to Brian Flamm, Matthew Han, Ryosuke Isobe, Curtis Takagi, Justin Virgili, Leize Zhu.
Application Number | 20210261718 17/316614 |
Document ID | / |
Family ID | 1000005627328 |
Filed Date | 2021-08-26 |
United States Patent
Application |
20210261718 |
Kind Code |
A1 |
Takagi; Curtis ; et
al. |
August 26, 2021 |
HYBRID COPOLYMER COMPOSITION FOR PROTECTING FOLDABLE DISPLAYS
Abstract
A polymer composition includes: a first proportion of an
aliphatic-diisocyanate terminated polyol; a second proportion of an
aromatic diisocyanate; a third proportion of an aromatic diamine
curative configured to extend a chain length of the
aliphatic-diisocyanate-terminated polyol and the aromatic
diisocyanate; a fourth proportion of a polyester polyol configured
to polymerize with the aliphatic-diisocyanate-terminated polyol;
and a fifth proportion of a high functionality dendrimer configured
to crosslink polymer chains of the
aliphatic-diisocyanate-terminated polyol. Further, the hybrid
copolymer can be configured to form a protective film layer in a
foldable electronic display, the foldable electronic display
including: a cover layer arranged over the protective film layer;
and an array of organic light-emitting diodes arranged beneath the
protective film layer.
Inventors: |
Takagi; Curtis; (Fremont,
CA) ; Han; Matthew; (Fremont, CA) ; Virgili;
Justin; (Fremont, CA) ; Isobe; Ryosuke;
(Fremont, CA) ; Flamm; Brian; (Fremont, CA)
; Zhu; Leize; (Newark, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tactus Technology, Inc. |
Fremont |
CA |
US |
|
|
Family ID: |
1000005627328 |
Appl. No.: |
17/316614 |
Filed: |
May 10, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16723797 |
Dec 20, 2019 |
|
|
|
17316614 |
|
|
|
|
62806808 |
Feb 16, 2019 |
|
|
|
62783067 |
Dec 20, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/64 20130101;
C08J 5/18 20130101; C08G 18/3819 20130101; C08G 18/7812 20130101;
C08J 2375/12 20130101; C08G 18/7628 20130101; C08G 18/348 20130101;
C08G 18/758 20130101; C08J 2375/06 20130101; C08J 2375/02
20130101 |
International
Class: |
C08G 18/76 20060101
C08G018/76; C08G 18/78 20060101 C08G018/78; C08G 18/75 20060101
C08G018/75; C08G 18/64 20060101 C08G018/64; C08G 18/38 20060101
C08G018/38; C08G 18/34 20060101 C08G018/34; C08J 5/18 20060101
C08J005/18 |
Claims
1. A polymer composition: comprising a first amount of urethane
linkages: connecting a first quantity of polyol segments to a
second quantity of a first subset of diisocyanates; and connecting
a third quantity of a crosslinker to a fourth quantity of a second
subset of diisocyanates; and comprising a second amount of urea
linkages connecting a fifth quantity of a curative to a sixth
quantity of a third subset of diisocyanates; exhibiting an impact
resistance characterized by a tan delta between 0.05 and 0.4 at
temperatures between -20 degrees Celsius and 85 degrees
Celsius.
2. The polymer composition of claim 1, wherein a film comprising
the polymer composition exhibits no measurable permanent
deformation after the film is repeatedly folded and unfolded around
a 2-millimeter radius mandrel at a frequency of 1 Hz for greater
than 200,000 cycles.
3. The polymer composition of claim 2, wherein the film is
configured to form a protective film layer in a foldable electronic
display, the foldable electronic display comprising: the protective
film layer: comprising the polymer composition; and exhibiting a
first thickness between 5 micrometers and 120 micrometers; and a
hard coat layer: comprising a resin material; and exhibiting: a
water contact angle of a surface of the hard coat layer equivalent
or greater than 110 degrees; a pencil hardness equivalent or
greater than H tested at a load of 250 grams; and a second
thickness between 2 micrometers and 30 micrometers.
4. The polymer composition of claim 2, wherein the film is
configured to form a protective film layer in a foldable electronic
display, the foldable electronic display comprising: the protective
film layer: comprising the polymer composition; and exhibiting a
first thickness between 5 micrometers and 120 micrometers; and a
pressure sensitive adhesive layer: comprising an adhesive material;
and exhibiting: a room temperature storage modulus between 10 kPa
and 250 kPa at 25 degrees Celsius; a storage modulus between 10 kPa
and 500 kPa at temperatures between -20 degrees Celsius to 85
degrees Celsius; and a second maximum tan delta equivalent or less
than 0.4; and a second thickness between 5 micrometers and 50
micrometers.
5. The polymer composition of claim 4, wherein the foldable
electronic display further comprises: an optical layer exhibiting a
third thickness between 5 micrometers and 100 micrometers; a hard
coat layer, exhibiting: a water contact angle of a surface of the
hard coat layer equivalent or greater than 110 degrees; a pencil
hardness equivalent or greater than H tested at a load of 250
grams; and a second thickness between 2 micrometers and 30
micrometers.
6. The polymer composition of claim 5, wherein the laminated film
comprises: the hard coat layer comprising the resin material
selected from the group comprising a (meth)acryl resin, an epoxy
resin, a silicone resin, an oxetane resin, a urethane resin, a
urethane (meth)acrylate resin; the protective film layer arranged
below the hard coat layer and above the optical layer; the optical
layer: selected from the group comprising a polymer substrate and a
glass substrate; and arranged below the protective film layer and
above the pressure sensitive adhesive layer; and the pressure
sensitive adhesive layer: comprising the adhesive material
comprising a resin; and arranged below the optical layer.
7. The polymer composition of claim 1, comprising a molar ratio of
the first amount of urethane linkages to the second amount of urea
linkages between two-to-five and six-to-five.
8. The polymer composition of claim 1, exhibiting: a haze value
less than 1.3 percent; a yellowness index less than 1.1; and a
surface roughness characterized by an arithmetic mean deviation
between 5 nanometers and 40 nanometers.
9. The polymer composition of claim 1, exhibiting: a
low-temperature storage modulus between 300 MPa and 1400 MPa at -20
degrees Celsius; and a high-temperature storage modulus between 10
MPa and 100 MPa at 85 degrees Celsius.
10. The polymer composition of claim 9, exhibiting: a first modulus
ratio between two percent and twenty percent after 5 weeks in
storage at -10 degrees Celsius; a second modulus ratio between two
percent and twenty percent after 5 weeks of storage at 23 degrees
Celsius; and a third modulus ratio between two percent and twenty
percent after 5 weeks in storage at 50 degrees Celsius.
11. The polymer composition of claim 1, exhibiting: a bulk density
between 1.1 and 1.4 g/cm.sup.3; and a void fraction between three
and twenty percent.
12. The polymer composition of claim 1, exhibiting a tan delta
curve characterized by a full width at half maximum between 70
degrees Celsius and 180 degrees Celsius.
13. A polymer composition: comprising: a first proportion of polyol
segments; a second proportion of polyisocyanates; a third
proportion of a curative; a fourth proportion of a soft polymer
chain; and a fifth proportion of a crosslinker; exhibiting a tan
delta curve characterized by: a low-temperature tan delta between
0.05 and 0.25 at -20 degrees Celsius; a high-temperature tan delta
between 0.05 and 0.30 at 85 degrees Celsius; and a maximum tan
delta less than 0.4 at temperatures between -20 degrees Celsius and
85 degrees Celsius.
14. The polymer composition of claim 13: exhibiting a storage
modulus between 10 MPa and 1400 MPa at temperatures between -20
degrees Celsius and 85 degrees Celsius; and exhibiting a room
temperature storage modulus between 50 MPa and 400 MPa at 20
degrees Celsius.
15. The polymer composition of claim 13: comprising a first amount
of urethane linkages: connecting the first proportion of polyol
segments to a first subset of the second proportion of
polyisocyanates; and connecting the third proportion of the
crosslinker to a second subset of the second proportion of
polyisocyanates; and comprising a second amount of urea linkages
connecting the third proportion of the curative to a third subset
of the second proportion of polyisocyanates.
16. The polymer composition of claim 13, exhibiting: a haze value
less than 1.3 percent; a yellowness index less than 1.1; and a
surface roughness characterized by an arithmetic mean deviation
between 5 nanometers and 40 nanometers.
17. The polymer composition of claim 16, exhibiting a temperature
resistance characterized by: a first haze ratio between negative
twenty percent and twenty percent after 5 weeks of storage at -10
degrees Celsius; a second haze ratio between negative twenty
percent and twenty percent after 5 weeks of storage at 23 degrees
Celsius; and a third haze ratio between negative twenty percent and
twenty percent after 5 weeks of storage at 50 degrees Celsius.
18. The polymer composition of claim 16, comprising a seventh
quantity of a UV stabilizer configured to reduce
environmentally-induced changes in yellowness index.
19. A polymer composition: comprising a first amount of urethane
linkages; exhibiting: a tan delta curve characterized by: a
low-temperature tan delta between 0.05 and 0.25 at -20 degrees
Celsius; a high-temperature tan delta between 0.05 and 0.30 at 85
degrees Celsius; and a maximum tan delta less than 0.4 at
temperatures between -20 degrees Celsius and 85 degrees Celsius; a
surface roughness characterized by an arithmetic mean deviation
between 5 nanometers and 40 nanometers; a haze value less than 1.3
percent; and a yellowness index less than 1.1; and wherein a film
comprising the polymer composition exhibits a bend height less than
0.5 millimeters after subjecting the film to a bend test.
20. The polymer composition of claim 19, comprising: a molar ratio
of the first amount of urethane linkages to a second amount of urea
linkages between two-to-five and six-to-five; a first proportion of
a polyisocyanate-terminated polyol; a second proportion of an
additional polyisocyanate; a third proportion of a curative; a
fourth proportion of a soft polymer chain; and a fifth proportion
of a crosslinker.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application is a Continuation In Part application of
U.S. patent application Ser. No. 16/723,797, filed on 20 Dec. 2019,
which claims the benefit of U.S. Provisional Application No.
62/806,808, filed on 16 Feb. 2019, and U.S. Provisional Application
No. 62/783,067, filed on 20 Dec. 2018, and is related to U.S.
patent application Ser. No. 15/895,971, filed on 29 Apr. 2018, each
of which are incorporated in their entireties by this
reference.
TECHNICAL FIELD
[0002] This invention relates generally to the field of hybrid
copolymer chemistry and more specifically to a new and useful
composition for protecting digital displays in the field of hybrid
copolymer chemistry.
BRIEF DESCRIPTION OF THE FIGURES
[0003] FIGS. 1A and 1B are schematic representations of the
composition;
[0004] FIG. 2 is a schematic representation of the composition;
[0005] FIGS. 3A, 3B, 3C, 3D, 3E, 3F, and 3G are schematic
representations of a foldable light-emitting diode display; and
[0006] FIG. 4 is a schematic representation of components of the
composition;
[0007] FIG. 5 is a graphical representation of tan delta curves
representative of examples of the composition.
DESCRIPTION OF THE EMBODIMENTS
[0008] The following description of embodiments of the invention is
not intended to limit the invention to these embodiments but rather
to enable a person skilled in the art to make and use this
invention. Variations, configurations, implementations, example
implementations, and examples described herein are optional and are
not exclusive to the variations, configurations, implementations,
example implementations, and examples they describe. The invention
described herein can include any and all permutations of these
variations, configurations, implementations, example
implementations, and examples.
1. Composition
[0009] As shown in FIGS. 1A and 1B, a polymer composition 100 for
protecting electronic displays includes: a first proportion of a
polyisocyanate-terminated polyol 110; a second proportion of an
additional polyisocyanate 120; a third proportion of a curative 130
configured to extend a chain length of the
polyisocyanate-terminated polyol 110 and the additional
polyisocyanate 120; a fourth proportion of a soft polymer chain 140
configured to polymerize with the polyisocyanate-terminated polyol
110 and the additional polyisocyanates 120; and a fifth proportion
of a high functionality crosslinker 150 configured to crosslink the
polyisocyanate-terminated polyol 110 and the additional
polyisocyanate.
[0010] As shown in FIG. 2, one variation of the polymer composition
100 includes: a first proportion of an
aliphatic-diisocyanate-terminated polyol 111; a second proportion
of an additional diisocyanate 121; a third proportion of an
aromatic diamine curative 131 configured to extend a chain length
of the aliphatic-diisocyanate-terminated polyol 111 and the
additional diisocyanate 121; a fourth proportion of a polyester
polyol 141 configured to polymerize with the first proportion of
aliphatic-diisocyanate-terminated polyol 111 and second proportion
of additional diisocyanate 121; and a fifth proportion of a high
functionality dendrimer 151 configured to crosslink polymer chains
of the aliphatic-diisocyanate-terminated polyol.
[0011] One variation of the polymer composition 100 includes a
molar ratio of a first number of urethane linkages 104 to a second
number of urea linkages 106 between two-to-five and six-to-five. In
this variation, the first number of urethane linkages 104: connect
a first quantity of polyether polyol segments 112 to a second
quantity of aliphatic diisocyanate terminations 114; connect a
third quantity of polyester polyol segments 142 to the second
quantity of the aliphatic diisocyanate terminations 114 and a
fourth quantity of additional diisocyanates 120; and connect a
fifth quantity of a high functionality crosslinker 150 to the
second quantity of the aliphatic diisocyanate terminations 114 and
the fourth quantity of additional diisocyanates 120. In this
variation, the second number of urea linkages 106 connect a sixth
quantity of an aromatic polyamine curative 132 to the second
quantity of the aliphatic diisocyanate terminations 114 and the
fourth quantity of additional diisocyanates 120.
[0012] In one variation, the polymer composition 100 includes: a
first proportion of a polyisocyanate-terminated polyol 110; a
second proportion of an additional polyisocyanate 120; a third
proportion of a curative 130; a fourth proportion of a soft polymer
chain 140 configured to interrupt crystallization of the first
quantity of the polyisocyanate-terminated polyol below 50 degrees
Celsius; and a high functionality crosslinker 150. In this
variation, the polymer composition 100 exhibits: a first storage
modulus between 300 MPa and 1400 MPa at -20 degrees Celsius; a
second storage modulus between 10 MPa and 100 MPa at 85 degrees
Celsius; a room temperature storage modulus between 50 MPa and 400
MPa at 20 degrees Celsius; and an elongation at break greater than
350%.
[0013] In one variation, the polymer composition 100 includes: a
first proportion of polyol chains 116; a second proportion of
polyisocyanates (e.g., polyisocyanate terminations 114 and
additional polyisocyanates 120); a third proportion of a curative
130; a fourth proportion of a soft polymer chain 140; and a fifth
proportion of a crosslinker 150. In this variation, the polymer
composition 100 exhibits an impact resistance represented by a tan
delta curve, the tan delta curve characterized by: a
low-temperature tan delta between 0.05 and 0.25 at -20 degrees
Celsius; a high-temperature tan delta between 0.05 and 0.30 at 85
degrees Celsius; and a maximum tan delta less than 0.4 at
temperatures between -20 degrees Celsius and 85 degrees
Celsius.
[0014] In one variation, the polymer composition 100 includes: a
first amount of urethane linkages 104 connecting a first quantity
of polyol segments 116 to a second quantity of a first subset of
diisocyanates 114 and connecting a third quantity of a crosslinker
150 to a fourth quantity of a second subset of diisocyanates (e.g.,
diisocyanate terminations 114 and/or additional diisocyanates 120);
and a second amount of urea linkages 106 connecting a fifth
quantity of a curative 130 to a sixth quantity of a third subset of
diisocyanates (e.g., diisocyanate terminations 114 and/or
additional diisocyanates 120). In this variation, the polymer
composition 100 exhibits: an impact resistance characterized by a
tan delta between 0.05 and 0.4 at temperatures between -20 degrees
Celsius and 85 degrees Celsius; and a room temperature storage
modulus between 50 MPa and 400 MPa at 20 degrees Celsius.
[0015] In one variation, the polymer composition 100 includes: a
first amount of urethane linkages 104 connecting a first quantity
of polyol segments 116 to a second quantity of a first subset of
diisocyanates 114 and connecting a third quantity of a crosslinker
150 to a fourth quantity of a second subset of diisocyanates (e.g.,
diisocyanate terminations 114 and/or additional diisocyanates 120);
and a second amount of urea linkages 106 connecting a fifth
quantity of a curative 130 to a sixth quantity of a third subset of
diisocyanates (e.g., diisocyanate terminations 114 and/or
additional diisocyanates 120). In this variation, the polymer
composition 100 exhibits: a set of optical properties including a
haze value less than 1.3 percent and a yellowness index less than
1.1; and a surface roughness between 5 nanometers and 40
nanometers.
[0016] In one variation, the polymer composition 100 includes a
first amount of urethane linkages 104. The polymer composition 100
exhibits a tan delta curve characterized by: a low-temperature tan
delta between 0.05 and 0.25 at -20 degrees Celsius; a
high-temperature tan delta between 0.05 and 0.30 at 85 degrees
Celsius; and a maximum tan delta less than 0.4 at temperatures
between -20 degrees Celsius and 85 degrees Celsius. Further, the
polymer composition 100 exhibits: a surface roughness characterized
by an arithmetic mean deviation between 5 nanometers and 40
nanometers; a haze value less than 1.3 percent; and a yellowness
index less than 1.1. Further, in this variation, a film including
the polymer composition 100 exhibits a bend height less than 0.5
millimeters after subjecting the film to a bend test.
2. Applications
[0017] Generally, as shown in FIGS. 1A and 1B, a polymer
composition 100 (e.g., a hybrid urea-urethane copolymer
composition) includes a polyisocyanate-terminated polyol 110,
additional polyisocyanates 120; a curative 130/chain length
extender, a soft polymer chain 140, and a high functionality
crosslinker 150 such that, when the polymer composition 100 is
cured in a continuous roll-to-roll process, the polymer composition
100 exhibits optical clarity (e.g., an optical transmission of
greater than 90% and/or voids with a characteristic size less than
100 nanometers); impact resistance (e.g., an impact resistance
characterized by a tan delta between 0.05 and 0.4 at temperatures
between -20 degrees Celsius and 85 degrees Celsius); mechanical
stability between -20.degree. C. and 85.degree. C. (e.g., a storage
modulus between 300 and 1400 MPa at -20.degree. C. and a storage
modulus between 10 and 100 MPa at 85.degree. C.);
flexibility/foldability (e.g., a repeatable 2-millimeter bend
radius), and UV stability. Furthermore, in prepolymer form, the
polymer composition 100 is workable via a roll-to-roll
manufacturing process, such as described in U.S. application Ser.
No. 15/895,971. When manufactured as a thin film, the polymer
composition 100 can function as a protective layer 102 in a
foldable electronic display (or touchscreen), thereby protecting a
display layer in the foldable electronic display from damage due to
impact, scratching, or abrasion while maintaining its optical and
mechanical properties after repetitive flexion (e.g., folding) of
the display. Additionally and/or alternatively, the polymer
composition 100 can function as a sponge film 103 configured to
provide impact resistance to a mechanical housing of a foldable
electronic display. Thus, without sacrificing optical properties,
the polymer composition 100 exhibits improved impact resistance and
durability to repetitive flexion of foldable electronic displays as
compared to other foldable display technology. For example, a
foldable electronic display including a protective layer 102
manufactured from the polymer composition 100 may exhibit minimal
optical and mechanical changes when folded with a 2-millimeter bend
radius 200,000 times.
[0018] The polymer composition 100 can exhibit the abovementioned
properties by effectively combining: qualities of aliphatic
isocyanate-polyol polymers, such as UV stability and slower
reaction rates during polymerization, qualities of aromatic
isocyanate-polyol polymers, such as high elongation at break (e.g.,
greater than 350 percent), and qualities of polyureas, such as
flexibility and durability. Furthermore, the polymer composition
100 includes: a curative 130 that yields a relatively long polymer
chain length in the polymer composition 100; and a high
functionality crosslinker 150 that yields a high bulk crosslink
density in the polymer composition 100. More specifically, the
curative 130 is configured to extend a chain length of the
polyisocyanate-terminated polyol 110 and the additional
polyisocyanates 120 via urea linkages 106 and the high
functionality crosslinker 150 is configured to crosslink the
polyisocyanate-terminated polyol 110 and additional polyisocyanates
in a radially-integrated pattern via urethane linkages 104, thereby
providing greater storage modulus at higher temperatures while
maintaining flexibility at lower temperatures. The polymer
composition 100 also includes the soft polymer chain 140 which is
configured to polymerize with the polyisocyanate terminations 114
of the polyisocyanate-terminated polyol 110 and the additional
polyisocyanates 120 to control crystallization of the
polyisocyanate-terminated polyol 110 at low temperatures, thereby
providing lower storage modulus at low temperatures when compared
with typical polyurethane compositions.
[0019] In one implementation, as shown in FIG. 2, the polymer
composition 100 includes an aliphatic-diisocyanate-terminated
polyol 111 as the polyisocyanate-terminated polyol 110; additional
diisocyanates 121 as the additional polyisocyanates 120; an
aromatic diamine curative 131 as the curative 130; a polyester
polyol 141 as the soft polymer chain 140; and a high functionality
dendrimer 151 as the high functionality crosslinker 150.
[0020] The polymer composition 100 can include a catalyst, which
aids in improving processing times. The catalyst can include any
polyurethane catalyst configured to initiate polyurethane and/or
polyurea polymerization that does not present environmental health
and safety concerns during the manufacturing process or in the
completed product (e.g., when included in a light-emitting diode
display). Additionally, the polymer composition 100 can include
additives, including but not limited to surfactants, de-foamers,
self-leveling agents, and/or wetting agents, which can reduce the
surface tension of the prepolymer mixture and thereby improve the
surface quality of a protective film manufactured from the polymer
composition 100.
[0021] Furthermore, the prepolymer mixture of the polymer
composition 100 is soluble in aprotic, polar organic solvents, such
as methyl ethyl ketone (hereinafter "MEK"), which can substantially
evaporate during the roll-to-roll manufacturing process while
reducing the viscosity of the prepolymer mixture.
3. Foldable Display
[0022] In one implementation, as shown in FIGS. 3A-3G, the polymer
composition 100 can be configured to form a protective film layer
102 in a foldable electronic display. As shown in FIG. 3A, the
polymer composition 100 can be configured to form a protective film
layer 102 for a foldable electronic display, the foldable
electronic display including: a foldable light-emitting diode
(hereinafter "LED") display (e.g., an array of organic light
emitting diodes); and a cover layer. The protective film layer 102
includes: a first proportion of the polyisocyanate-terminated
polyol 110; the second proportion of additional polyisocyanates
120; a third proportion of the curative 130; a fourth proportion of
the soft polymer chain 140; and the fifth proportion of a high
functionality crosslinker.
[0023] In one implementation, the foldable electronic display
includes a protective film layer 102 arranged above the cover layer
and secured via an pressure sensitive adhesive as shown in FIG. 3A.
In another implementation, the foldable electronic display includes
a protective film layer 102 arranged between the cover layer and
the foldable electronic display as shown in FIG. 3C. In yet another
implementation, the foldable electronic display includes a first
protective film layer 102 arranged above the cover layer and a
second protective film layer 102 arranged beneath the cover layer
both secured via layers of pressure sensitive adhesive.
Additionally or alternatively, the foldable electronic display can
include pressure sensitive adhesive to adhere the cover layer to
the protective film or the protective film layer 102 to the
foldable electronic display.
[0024] In one implementation, as shown in FIGS. 3D-3F, the polymer
composition 100 can be configured to form a protective film layer
102 integrated into a laminated film in a foldable electronic
display. In this implementation, the laminated film can include: a
hard coat layer; an optical layer; the protective film layer 102;
and/or an pressure sensitive adhesive layer (e.g., an optically
clear adhesive layer). The laminated film can include any
combination of these layers and can also be configured to include
additional layers. For example, the laminated film can include the
protective film layer 102 and the pressure sensitive adhesive
layer. In another example, the laminated film can include the
protective film layer 102 and the hard coat layer. In yet another
example, the laminated film can include the hard coat layer, the
protective film layer 102, the optical layer, and the pressure
sensitive adhesive layer (e.g., an optically clear adhesive
layer).
[0025] In this implementation, the protective film layer, including
the polymer composition 100, can exhibit a thickness between 5
micrometers and 120 micrometers.
[0026] In this implementation, the laminated film can include the
hard coat layer including any combination of resins, inorganic
materials, and/or organic materials. For example, the hard coat
layer can include: a resin such as a (meth)acryl resin, an epoxy
resin, a silicone resin, an oxetane resin, a urethane resin, an
urethane (meth)acrylate resin, and/or any combination of these
resins; an inorganic material such as silica, alumina, zirconia,
and/or any combination of these inorganic materials; and/or an
organic material such polysilsesquioxane or a mixture thereof.
Further, the hard coat layer can exhibit: a water contact angle of
the hard coat layer surface greater than or equal to 110 degrees; a
pencil hardness tested at 250 grams load greater than or equal to
H; and a thickness between 2 micrometers and 30 micrometers.
[0027] Additionally, in this implementation, the laminated film can
include an optical layer including a polymeric or glass substrate.
In one example, the optical layer can include a polymer substrate
such as polyethylene terephthalate, polyethylene naphthalate,
colorless polyimide, cyclic olefin copolymer, polysulfide,
polycarbonate, and/or acrylic. In another example, the optical
layer can include a foldable glass substrate such as ultra-thin
glass. Further, the optical layer can exhibit a thickness between 5
micrometers and 100 micrometers.
[0028] Additionally, in this implementation, the laminated film can
include the pressure sensitive adhesive film layer. In one example,
the pressure sensitive adhesive layer can include a silicone
including resin, acryl based resin, and/or urethane based resin or
copolymer thereof based resin. The pressure sensitive adhesive
layer can exhibit: a room temperature storage modulus between 10
kPa and 250 kPa at 25 degrees Celsius; a storage modulus between 10
kPa and 500 kPa at temperatures between -20 degrees Celsius and 85
degrees Celsius; a maximum tan delta equivalent or less than 0.40;
and a thickness between 5 micrometers and 50 micrometers.
[0029] In one example, as shown in FIG. 3F, the laminated film can
include: the hard coat layer; the protective film layer 102
arranged beneath the hard coat layer and above the optical layer;
the optical layer arranged beneath the protective film layer 102
and above the pressure sensitive adhesive layer; and the pressure
sensitive adhesive layer arranged below the optical layer. In
another example, as shown in FIG. 3G, the laminated film can
include: the hard coat layer; the optical layer arranged beneath
the hard coat layer and above the protective film layer 102; the
protective film layer 102 arranged beneath the optical layer and
above the pressure sensitive adhesive layer; and the pressure
sensitive adhesive layer arranged below the protective film layer
102.
[0030] In one implementation, in which the polymer composition 100
is configured to form the protective film layer 102, the polymer
composition 100 can exhibit a release liner adhesion between 0.05
Newtons-per-25-millimeters and 1.0 Newtons-per-25-millimeters. In
another implementation, in which the polymer composition 100 is
configured to form the protective film layer 102, the polymer
composition 100 can exhibit a release liner adhesion between 0.05
Newtons-per-25-millimeters and 0.5 Newtons-per-25-millimeters.
[0031] The polymer composition 100 can be manufactured via a
roll-to-roll manufacturing process to form a protective film 102
configured for insertion in a foldable electronic display stack.
For example, the polymer composition 100 can form a protective film
exhibiting: a thickness between 5 micrometers and 120 micrometers;
and a flexibility characterized by bending the film layer around a
two-millimeter mandrel, unfolding the film, and observing no damage
or change in the protective film 102 after repeating this process
over 200,000 times. Additionally, the protective film 102 exhibits
desirable optical qualities including: transmission greater than
ninety percent; haze less than one percent; and clarity greater
than ninety percent.
[0032] In another implementation, as shown in FIG. 3B, the polymer
composition 100 can be manufactured to form a sponge layer 103 in a
foldable electronic display, the foldable electronic display
including: a foldable light-emitting diode (hereinafter "LED")
display; and a mechanical housing arranged below the LED display
and above the sponge layer 103. Additionally or alternatively, the
foldable electronic display can include a pressure sensitive
adhesive layer; For example, the polymer composition 100 can form
the sponge layer 103 exhibiting: a thickness between 5 micrometers
and 120 micrometers; and an elongation at break greater than 350
percent.
[0033] However, a foldable electronic display including the
protective film layer 102 or the sponge layer 103 can include
additional layers or components not described above or shown in
FIGS. 3A-3G. Alternatively, a foldable electronic display including
the protective film layer 102 or the sponge layer 103 can include
fewer layers or components shown in FIGS. 3A-3G.
4. Polymer Properties
[0034] The polymerized form of the polymer composition 100 exhibits
qualities that are favorable for use as a protective film (i.e.,
protective layer 102) within an electronic display. More
specifically, the polymerized form of the polymer composition 100
exhibits qualities favorable for insertion as a protective film
layer 102 within a foldable electronic display, such as an LED
display (e.g., an organic LED display). In particular, the polymer
composition 100 can be configured to exhibit qualities such
that--when inserted as a protective film layer 102 within a
foldable electronic display--the protective film layer 102 exhibits
increased impact resistance, increased bending performance, and
relatively high reliability (e.g., under extreme environmental
conditions). Therefore, the polymer form of the polymer composition
100 exhibits: higher storage modulus at high temperatures and lower
storage modulus at lower temperatures than a typical
polyurethane-based or poly(urea-urethane)-based elastomer, thereby
enabling a thin film of the polymer composition 100 (e.g., with a
thickness between 5 and 120 micrometers) to protect the electronic
display from impact, scratching, and abrasion over a wide range of
temperatures (-20.degree. C. to 85.degree. C.); lower loss factor
(or "tan delta") over a wide range of temperatures, thereby
enabling a thin film of the polymer composition 100 to quickly
absorb force with high elasticity; high flexibility, thereby
enabling the polymer composition 100 to repeatedly bend around a
small radius without noticeable deformation or degradation; optical
clarity, which enables a user to view an image rendered on the
electronic display without significant optical aberrations; and UV
stability (e.g., UV resistance), thereby preserving perceived color
of images rendered by the underlying electronic display.
4.1 Storage Modulus
[0035] The polymerized polymer composition 100 can exhibit a
storage modulus between 50 MPa and 400 MPa at 20.degree. C. (as
measured via dynamic mechanical analysis testing using a tension
clamp from -70.degree. C. and .degree. C. with a 2.degree. C./min
warming rate, an oscillation rate of 1 Hz, and a force control of
0.1 N), depending on factors (further discussed below) including:
the functionality and weight percentage of the curative 130
included in the polymer composition 100; the molecular weight and
type of the polyol in the polyisocyanate terminated polyol 110; the
weight percentage and chemistry of the additional polyisocyanates
120; the molecular weight and weight percentage of the soft polymer
chain 140; and the weight percentage and degree of functionality of
the high functionality crosslinker 150.
[0036] The polymerized polymer composition 100 can exhibit
relatively low variation in storage modulus over its operating
temperature range. For example, the polymer composition 100 can
exhibit a storage modulus between 300 MPa and 1400 MPa at
-20.degree. C., a storage modulus between 50 and 400 MPa at
20.degree. C., and a storage modulus between 10 MPa and 100 MPa at
85.degree. C. Furthermore, the polymerized polymer composition 100
can exhibit a relatively high glass transition temperature, such as
between 40.degree. C. and 75.degree. C. (as measured via dynamic
mechanical analysis testing using a tension clamp from -70.degree.
C. to 150.degree. C. with a 2.degree. C./min heating rate, an
oscillation rate of 1 Hz, and a force control of 0.1 N). The low
variation in storage modulus and high glass transition temperature
of the polymer composition 100 results in part from the hybrid
nature of the copolymer, wherein hard polymer segments include the
isocyanate terminations 114 of the polyisocyanate-terminated polyol
110, the additional polyisocyanates 120, and the curative 130 chain
extender; and wherein soft polymer segments include the polyol
segments of the polyisocyanate-terminated polyol no and the soft
polymer segment. Generally, the hard polymer segments maintain the
rigidity of the polymer composition 100 at high temperatures while
the soft polymer segments prevent excess hardening of the polymer
composition 100 at low temperatures. Thus, temperature-dependent
storage modulus characteristics of the polymer composition 100 may
be tuned by adjusting the weight percentage of the hard polymer
segment components in relation to the weight percentage of the soft
polymer segment components.
[0037] The polymer composition 100 can be characterized by a
modulus ratio (i.e., a change in the storage modulus of the polymer
composition 100 defined as the final storage modulus divided by the
initial storage modulus expressed as a percentage and subtracting
100 percent) responsive to exposure to temperatures within
different temperatures ranges for a set duration. In one
implementation, the polymer composition 100 can: exhibit a first
modulus ratio between two percent and twenty percent after 5 weeks
of storage at a low holding temperature of -10 degrees Celsius; a
second modulus ratio between two percent and twenty percent after 5
weeks of storage at a moderate holding temperature of 23 degrees
Celsius; and a third modulus ratio between two percent and twenty
percent after 5 weeks at an upper holding temperature of 50 degrees
Celsius.
[0038] For example, the first modulus ratio of the polymer
composition 100 can be characterized by: at a first time prior to a
first test period, measuring a first initial storage modulus of the
polymer composition 100; during the first test period, storing the
polymer composition 100 at -10 degrees Celsius for a duration of 5
weeks; at a second time succeeding the first test period, measuring
a first final storage modulus of the polymer composition 100; and,
calculating the first modulus ratio of the polymer composition 100
as a ratio of the first final storage modulus to the first initial
storage modulus. The second modulus ratio of the polymer
composition 100 can be characterized by: at a first time prior to a
second test period, measuring a second initial storage modulus of
the polymer composition 100; during the second test period, storing
the polymer composition 100 at 23 degrees Celsius for a duration of
5 weeks; at a second time succeeding the second test period,
measuring a second final storage modulus of the polymer composition
100; and, calculating the second modulus ratio of the polymer
composition 100 as a ratio of the second final storage modulus to
the second initial storage modulus. The third modulus ratio of the
polymer composition 100 can be characterized by: at a first time
prior to a third test period, measuring a third initial storage
modulus of the polymer composition 100; during the third test
period, storing the polymer composition 100 at 50 degrees Celsius
for a duration of 5 weeks; at a second time succeeding the third
test period, measuring a third final storage modulus of the polymer
composition 100; and, calculating the third modulus ratio of the
polymer composition 100 as a ratio of the third final storage
modulus to the third initial storage modulus.
4.2 Tan Delta
[0039] The polymer composition 100 can exhibit an impact resistance
represented by a tan delta (or dissipation or loss factor) between
0.05 and 0.40 at temperatures between -20 degrees Celsius and 85
degrees Celsius. The polymer composition 100 can therefore exhibit
relatively low variation in tan delta over a wide range of
temperature. By maintaining this relatively low tan delta (e.g.,
less than 0.40) across this wide range of temperatures, the polymer
composition 100 can exhibit increased impact resistance, increased
folding resistance, and increased elastic recovery across this wide
range of temperatures.
[0040] In one implementation, the polymer composition 100 can
exhibit: a low-temperature tan delta between 0.05 and 0.25 at -20
degrees Celsius; a high-temperature tan delta between 0.05 and 0.30
at 85 degrees Celsius; and a maximum tan delta less than 0.40 at
temperatures between -20 degrees Celsius and 85 degrees Celsius. In
one example, the polymer composition 100 exhibits: a
low-temperature tan delta between 0.05 and 0.15 at -20 degrees
Celsius; a high-temperature tan delta between 0.10 and 0.25 at 85
degrees Celsius; and a maximum tan delta less than 0.30 at
approximately (e.g., within 3 degrees Celsius) 24 degrees
Celsius.
[0041] In this implementation, as described above, the polymer
composition 100 can exhibit a maximum tan delta less than 0.40 at
temperatures between -20 degrees Celsius and 85 degrees Celsius.
Examples of the maximum tan delta (or "Peak Tan Delta") and
corresponding temperatures (or "Tan Delta Peak Temp") for the
polymer composition 100 are listed below in Table 1.
TABLE-US-00001 TABLE 1 Tan Delta Peak Peak Temp Tan Example
(.degree. C.) Delta Example #1 24, 108 0.18, 0.16 Example #2 60
0.22 Example #3 60 0.20 Example #4 52 0.22 Example #5 24 0.20
Example #6 12 0.21 Example #7 12 0.20
[0042] Further, as shown in FIG. 5, the impact resistance of the
polymer composition 100 can be represented by a tan delta curve. In
particular, this tan delta curve represents changes in the tan
delta of the polymer composition 100 as a function of
temperature.
[0043] More specifically, FIG. 5 depicts seven variations of the
tan delta curve, each of these variations representative of an
example of the polymer composition 100 included in Table 1.
[0044] In each of the seven examples of the polymer composition 100
included in Table 1, the polymer composition 100 includes: a first
proportion of a polyisocyanate-terminated polyol 110; a second
proportion of additional polyisocyanates 120; a third proportion of
a curative 130/chain length extender; a fourth proportion of a soft
polymer chain 140; a fifth proportion of a high functionality
crosslinker 150; a sixth proportion of a catalyst; and a seventh
proportion of a surface additive.
[0045] In particular, the polymer composition 100 of Example #1
includes a first proportion of a polyether
polyisocyanate-terminated polyol 110 exhibiting an average
molecular weight between 650 g/mol and 2600 g/mol as the first
proportion of the polyisocyanate-terminated polyol 110. The polymer
composition 100 of Example #1 further includes an eighth proportion
of a UV stabilizer.
[0046] The polymer composition 100 of Example #2 includes a first
proportion of a polycaprolactone polyisocyanate-terminated polyol
no exhibiting an average molecular weight between 500 and 2600
g/mol as the polyisocyanate-terminated polyol 110.
[0047] Similarly, the polymer composition 100 of Example #3
includes the first proportion of a polycaprolactone
polyisocyanate-terminated polyol no as the
polyisocyanate-terminated polyol 110. However, the polymer
composition 100 of Example #3 further includes an eighth proportion
of a UV stabilizer.
[0048] The polymer composition 100 of Example #4 includes the first
proportion of polyisocyanate-terminated polyol 110 including a 3 to
1 (w/w) ratio of: a polycaprolactone polyisocyanate-terminated
polyol exhibiting an average molecular weight between 500 g/mol and
2600 g/mol; and a polyether polyisocyanate-terminated polyol
exhibiting an average molecular weight between 650 g/mol and 2600
g/mol.
[0049] The polymer composition 100 of Example #5 includes the first
proportion of polyisocyanate-terminated polyol 110 including a 3 to
2 (w/w) ratio of: a polyether polyisocyanate-terminated polyol
exhibiting an average molecular weight between 650 g/mol and 1000
g/mol; and a polyether polyisocyanate-terminated polyol exhibiting
an average molecular weight between 1000 g/mol and 2600 g/mol.
[0050] The polymer composition 100 of Example #6 includes the first
proportion of polyisocyanate-terminated polyol 110 including a 1 to
1 (w/w) ratio of: a polyether polyisocyanate-terminated polyol
exhibiting an average molecular weight between 650 g/mol and 1000
g/mol; and a polyether polyisocyanate-terminated polyol exhibiting
an average molecular weight between 1000 g/mol and 2600 g/mol.
[0051] The polymer composition 100 of Example #7 includes a first
proportion of the polyisocyanate-terminated polyol 110 including a
2 to 3 (w/w) ratio of a polyether polyisocyanate-terminated polyol
exhibiting an average molecular weight between 650 g/mol and 1000
g/mol; and a polyether polyisocyanate-terminated polyol exhibiting
an average molecular weight between 1000 g/mol and 2600 g/mol.
[0052] In one implementation, the impact resistance of the polymer
composition 100 can be represented by a tan delta curve
characterized by a full width at half maximum between 70 degrees
Celsius and 180 degrees Celsius. In this implementation, the tan
delta curve can include: a low-temperature tan delta between 0.05
and 0.25 at -20 degrees Celsius; a high-temperature tan delta
between 0.05 and 0.30 at 85 degrees Celsius; and a maximum tan
delta less than 0.40 at temperatures between -20 degrees Celsius
and 85 degrees Celsius. As shown in FIG. 5, the polymer composition
100 can thus exhibit an impact resistance characterized by a tan
delta curve exhibiting a relatively broad, wide peak, rather than a
steep, narrow peak. Therefore, by maintaining this relatively high
full width at half maximum (e.g., between 70 degrees Celsius and
180 degrees Celsius), the polymer composition 100 can exhibit
increased impact resistance and high elasticity across a large
temperature range.
4.3 Flexibility
[0053] The polymerized polymer composition 100 can also exhibit
high static and dynamic flexibility. The static flexibility of the
polymerized hybrid copolymer can be characterized by bending a thin
film of the polymer composition 100 around a 2-millimeter radius
mandrel for four hours at 25.degree. C. without the thin film of
the polymer composition 100 exhibiting permanent deformation or
degradation of optical or mechanical properties. The dynamic
flexibility of the polymerized polymer composition 100 can be
characterized by repeatedly bending the thin film of the polymer
composition 100 around a 2-millimeter radius mandrel at a frequency
of 1 Hz for 200,000 cycles without the thin film of the polymer
composition 100 exhibiting permanent deformation or degradation of
optical or mechanical properties.
[0054] In one implementation, a film formed of the polymer
composition 100 can exhibit a bend height less than 0.50
millimeters when subjected to a bend test. In this implementation,
a bend test can include a series of bend test cycles (e.g., 1,000
bend test cycles, 100,000 bend test cycles, 200,000 bend test
cycles), each bend test cycle including bending and unbending the
film, formed of the polymer composition 100, around a 1-millimeter
radius surface (e.g., a 1-millimeter radius mandrel). After
completion of the bend test, the bend height can be measured by
laying the film on a flat surface--such that a concave surface of
the film faces the flat surface--and measuring a perpendicular
distance between the flat surface and a center of the film. In one
example, the film can exhibit a bend less than 0.20 millimeters
when subjected to a bend test including at least 1,000 bend test
cycles.
[0055] Additionally and/or alternatively, in one implementation, a
film formed of the polymer composition 100 can be visually
inspected at the completion of testing for evidence of cracking,
permanent creasing, or changes in haze.
[0056] The flexibility and/or foldability of the polymer
composition 100 may be tuned, in part, by adjusting the proportions
of the curative 130 and the high functionality crosslinker 150,
which affects the bulk crosslinking density of the polymer
composition 100. Furthermore, the flexibility and/or foldability of
the polymer composition 100 can be modified by adjusting the
molecular weight and type of the polyol in the polyisocyanate
terminated polyol 110; the weight percentage and chemistry of the
additional polyisocyantes 120; the molecular weight type and weight
percentage of the soft polymer chain 140; and the weight percentage
of the high functionality crosslinker 150. In one implementation,
the polymer composition 100 can exhibit a bulk density between 1.1
and 1.4 g/cm.sup.3 and a void fraction between three and twenty
percent, thereby enabling enhanced impact performance of the
polymer composition 100.
4.4 Optical Properties
[0057] Furthermore, the polymerized hybrid copolymer can exhibit
high optical clarity. For example, the polymerized polymer
composition 100 can exhibit optical transmission greater than 90%,
haze less than 1.3%, clarity greater than 90%; and CIE 1976 Color
Scale values of L* greater than 90, a* greater than -1.0 and less
than 1.0, and b* greater than -1.0 and less the 1.0 (e.g., measured
according to ASTM D6290 with a 10-degree observer angle and
Illuminant D65); and a yellowness index equivalent to or less than
1.1. The optical properties are enabled by the amorphous structure
of the soft polymer segment of the polymer composition 100 and
control over the degree of crystallinity and crystallite size of
the hard segment. However, the polymerized polymer composition 100
may exhibit properties different than those described above when
manufactured with an alternative manufacturing method (e.g., such
as spray coating).
[0058] In one implementation, the polymer composition 100 can
exhibit a set of optical properties including a haze value
equivalent or less than 1.3 percent and a yellowness index
equivalent or less than 1.1. In this implementation, the haze value
can be measured according to ASTM D1003, Procedure A, with
Illuminant C. The Yellowness Index can be measured according to
ASTM D1925 with a 2-degree observer angle and Illuminant C.
[0059] Additionally, the polymer composition 100 can exhibit a
surface roughness below a threshold surface roughness such that the
haze value--which may be impacted by changes in surface
roughness--falls below 1.3 percent. Therefore, the polymer
composition 100 can exhibit a surface roughness less than 40
nanometers. In one example, the polymer composition 100 can
exhibit: a haze value less than 1.25 percent; a yellowness index
equivalent or less than 1.0; a surface roughness represented by an
arithmetic mean deviation (or "Ra") between 5 nanometers and 40
nanometers; and a thickness between 5 micrometers and 120
micrometers.
[0060] Further, the polymer composition 100 can exhibit the set of
optical properties including a UV resistance characterized by: a
haze ratio between -20 percent and 20 percent after 72 hours of UV
exposure; and a delta yellowness index between zero and 1.5 after
72 hours of UV exposure.
[0061] For example, the haze ratio of the polymer composition 100
can be characterized by: at a first time prior to a test period,
measuring an initial haze value of the polymer composition 100;
during the test period, exposing the polymer composition 100 to UV
light for 72 hours; at a second time succeeding the test period,
measuring a final haze value of the polymer composition 100; and,
calculating a haze ratio of the polymer composition 100 as a ratio
of the final haze value to the initial haze value. Additionally,
the haze ratio can be expressed as a percentage by converting this
ratio, of the final haze value to the initial haze value, to a
percentage (e.g., by multiplying by 100 percent) and subtracting
100 percent.
[0062] Similarly, the delta yellowness index of the polymer
composition 100 can be characterized by: at a first time prior to a
test period, measuring an initial yellowness index of the polymer
composition 100; during the test period, exposing the polymer
composition 100 to UV light for 72 hours; at a second time
succeeding the test period, measuring a final yellowness index of
the polymer composition 100; and, calculating the delta yellowness
index of the polymer composition 100 as a difference between the
initial yellowness index and the final yellowness index.
[0063] In particular, in one example, to characterize the delta
yellowness index of the polymer composition 100, a portion (e.g., a
two-inch by two-inch film) of the polymer composition 100 can be
extracted (e.g., cut) for analysis. This portion of the polymer
composition 100 can then be: set on an acrylate sheet; and,
together with the acrylate sheet, placed within a UV test chamber
including a UV lamp defining a distance of approximately (e.g.,
within one centimeter) 15 centimeters between the portion of the
polymer composition 100 and the UV lamp and defining a power output
of approximately (e.g., within 5 percent) 15 Watts. Once the
portion of the polymer composition 100 is placed within the UV test
chamber, the portion of the polymer composition 100 can be exposed
to UV light by powering on the UV lamp. In this example, the
portion of the polymer composition 100 can be removed from UV
exposure at set intervals to measure a series of yellowness index
values, such as at zero hours, 24 hours, 48 hours, and 72 hours.
The delta yellowness index can then be measured as a difference
between a final yellowness index value, in the series of yellowness
index values, recorded at 72 hours and a first yellowness index
value, in the series of yellowness index values, recorded at zero
hours.
[0064] Additionally, in this example, the portion of the polymer
composition 100 can be removed from UV exposure at these set
intervals to measure a series of haze values. The haze ratio can
then be measured as a ratio of a final haze value, in the series of
haze values, recorded at 72 hours, to a first haze value, in the
series of haze values, recorded at zero hours. The delta haze ratio
can then be represented as a percentage by converting this ratio,
of the final haze value to the first haze value, to a percentage
(e.g., by multiplying by 100 percent) and subtracting 100
percent.
[0065] Further, the polymer composition 100 can exhibit the set of
optical properties including a temperature resistance characterized
by: a first haze ratio between -20 percent and 20 percent after 5
weeks of storage at -10 degrees Celsius; a second haze ratio
between -20 percent and 20 percent after 5 weeks of storage at 23
degrees Celsius; and a third haze ratio between -20 percent and 20
percent after 5 weeks of storage at 50 degrees Celsius.
[0066] For example, the first haze ratio of the polymer composition
100 can be characterized by: at a first time prior to a first test
period, measuring an first initial haze value of the polymer
composition 100; during the test period, storing the polymer
composition 100 at -10 degrees Celsius for a duration of 5 weeks;
at a second time succeeding the test period, measuring a first
final haze value of the polymer composition 100; and, calculating a
first haze ratio of the polymer composition 100 as a ratio of the
first final haze value to the first initial haze value. Further,
the second haze ratio of the polymer composition 100 can be
characterized by: at a first time prior to a second test period,
measuring a second initial haze value of the polymer composition
100; during the second test period, storing the polymer composition
100 at 50 degrees Celsius for a duration of 5 weeks; at a second
time succeeding the second test period, measuring a second final
haze value of the polymer composition 100; and, calculating a
second haze ratio of the polymer composition 100 as a ratio of the
second final haze value to the second initial haze value. The third
haze ratio can be calculated by implementing similar
techniques.
[0067] In one variation, the polymer composition 100 can include a
proportion of a UV absorber configured to increase UV resistance of
the polymer composition 100. In particular, the polymer composition
100 can include the proportion of the UV absorber to minimize the
delta yellowness index of the polymer composition 100, such that
the polymer composition 100 exhibits increased resistance to UV
exposure. In one implementation, the polymer composition 100 can
include a proportion of benzotriazoles as the proportion of the UV
absorber. In another implementation, the polymer composition 100
can include a proportion of antioxidants as the proportion of the
UV absorber. In yet another implementation, the polymer composition
100 can include a proportion of hindered amine stabilizers as the
proportion of the UV absorber. Additionally and/or alternatively,
the polymer composition 100 can include any combination of
benzotriazoles, antioxidants, and/or hindered amine stabilizers as
the proportion of the UV absorber.
5. Prepolymer Properties
[0068] The prepolymer form of the polymer composition 100 also
exhibits qualities that are favorable to thin-film manufacturing
techniques, such as a roll-to-roll manufacturing process.
Therefore, the prepolymer form of the polymer composition 100
exhibits: low viscosity, thereby enabling the prepolymer mixture to
be distributed via a slot-die and to self-level within a reasonable
manufacturing time; solubility in commonly used organic solvents in
the coatings field; low surface tension such that the prepolymer
mixture cures without the appearance of flow lines and other
surface defects; and a sufficiently long pot-life to enable coating
with a slot die.
[0069] The prepolymer form of the polymer composition 100 exhibits
a viscosity less than 3500 centipoise, such that a thin film of the
polymer composition 100 can be coated and fully or partially cured
using a roll-to-roll manufacturing process. The viscosity of the
prepolymer form of the polymer composition 100 is controlled by
adjusting the weight percentage in a solvent (e.g., a smaller
weight percent resulting in a lower viscosity), which may be
adjusted between 20% and 80% solids, depending on the particular
solvent included in the prepolymer mixture; solvent type, and the
bulk molecular weight of the components of the prepolymer form of
the polymer composition 100.
[0070] The prepolymer form of the polymer composition 100 also
exhibits a low surface tension due to the inclusion of additives,
including but not limited to surfactants, de-foamers, self-leveling
agents, and/or wetting agents. Therefore, the polymer composition
100 exhibits a negative correlation between the weight percentage
of the additives and the surface tension of the prepolymer
mixture.
[0071] Furthermore, the prepolymer form of the polymer composition
100 also exhibits a tuned pot-life that is long enough such that
the prepolymer mixture can be coated using a slot-die without
curing prematurely, while also being short enough to mitigate any
imprinting defects due to insufficient curing and/or incomplete
drying during the combined drying/curing process. The pot-life of
the prepolymer mixture is controlled by: the weight proportion and
chemistry of the catalyst; temperature; the weight proportion of
the aliphatic or mixture of aliphatic and aromatic polyisocyanate
120; the overall solids content (i.e. the number of reactive
species) of the prepolymer; and the ratio of polyurea linkage to
polyurethane linkage generating groups in the prepolymer.
[0072] However, the prepolymer form of the polymer composition 100
can be tuned to exhibit different viscosities, different surface
tensions, and/or different pot-lives for other polymer
manufacturing processes, such as spray-coating, dip-coating,
moulding, compressing, transferring, injecting, blowing, or other
roll-to-roll processes such as gravure, reverse gravure, micro
gravure, reverse roll, flex bar, rod, wire bar, knife over roll
coating, etc.
6. Hybrid Copolymer Composition
[0073] As shown in FIGS. 1A and 1B, the polymer composition 100 is
a crosslinked copolymer containing hard polymer segments and soft
polymer segments resulting from the polymerization of molecular
components including: a first proportion of
polyisocyanate-terminated polyol 110; a second proportion of
additional polyisocyanates 120; a third proportion of curative 130
(or "chain length extender"); a fourth proportion of soft polymer
chain 140; and a fifth proportion of high functionality crosslinker
150. The polymer composition 100 can also include a catalyst and
additives, such as wetting agents, de-foamers, surfactants, etc. to
improve the prepolymer properties of the polymer composition 100,
as described above, for thin film manufacturing techniques.
[0074] In one implementation, the polymer composition 100 includes
an aliphatic-diisocyanate-terminated polyol 111 as the
polyisocyanate-terminated polyol 110, a mixture of aliphatic
polyisocyanate and aromatic polyisocyanate 121 as the additional
polyisocyanates 120, an aromatic diamine curative 131 as the
curative 130, a polyester polyol 141 as the soft polymer chain 140,
and a high functionality dendrimer 151 as the high functionality
crosslinker 150. Thus, in this implementation, the polymer
composition 100 includes: a first proportion of an
aliphatic-diisocyanate-terminated polyol 111; a second proportion
including aliphatic polyisocyanate and aromatic polyisocyanate 121;
a third proportion of an aromatic diamine curative 131 configured
to extend a chain length of the aliphatic-diisocyanate-terminated
polyol 111, the aliphatic polyisocyanate, and the aromatic
polyisocyanate; a fourth proportion of a polyester polyol 141
configured to polymerize with the aliphatic-diisocyanate-terminated
polyol 111, the aliphatic polyisocyanate, and the aromatic
polyisocyanate; and a fifth proportion of a high functionality
dendrimer 151 configured to crosslink the
aliphatic-diisocyanate-terminated polyol 111, the aliphatic
polyisocyanate, and the aromatic polyisocyanate.
[0075] Different combinations of polymers and isocyanate
terminations 114 can be included in these proportions of the
polymer composition 100 in order to achieve the desired mechanical
and optical characteristics. For example, in a first
implementation, the polymer composition 100 can include: a
12-fold-hydrogenated-methylene-diphenyl-diisocyanate-terminated
polybutylene adipate as the polyisocyanate-terminated polyol; an
isophorone diisocyanate as the aliphatic polyisocyanate 120;
hydroquinone bis(2-hydroxyethyl)ether as the curative 130; a
polyester polyol 141 as the soft polymer chain 140; and a dendritic
polyester polyol exhibiting a functionality of six as the high
functionality crosslinker 150. Thus, in this implementation, the
polymer composition 100 includes: a first proportion of
12-fold-hydrogenated-methylene-diphenyl-diisocyanate-terminated
polybutylene adipate; a second proportion of isophorone
diisocyanate; a third proportion of hydroquinone
bis(2-hydroxyethyl)ether; a fourth proportion of a polyester polyol
141; and a fifth proportion of a dendritic polyester polyol
exhibiting a functionality of six.
[0076] In a second implementation, the polymer composition 100 can
include: a
12-fold-hydrogenated-methylene-diphenyl-diisocyanate-terminated
poly(tetramethylene ether) glycol as the polyisocyanate-terminated
polyol 110; a mixture of
12-fold-hydrogenated-methylene-diphenyl-diisocyanate 122 and a
tetramethylxylene diisocyanate 123 as the additional
polyisocyanate; a set of isomers of diethyl toluene diamine 131 as
the curative 130; a polycaprolactone polyol diol 141 as the soft
polymer chain 140; and a dendritic polyester polyol 151 exhibiting
a functionality greater than five as the high functionality
crosslinker 150. Thus, in this implementation, the polymer
composition 100 includes: a first proportion of a
12-fold-hydrogenated-methylene-diphenyl-diisocyanate-terminated
poly(tetramethylene ether) glycol 111; a second proportion of
additional polyisocyanates 120 including a first quantity of
12-fold-hydrogenated-methylene-diphenyl-diisocyanate 122 and a
second quantity of tetramethylxylene diisocyanate 123; a third
proportion of a set of isomers of diethyl toluene diamine 131; a
fourth proportion of a polycaprolactone polyol diol 141; and a
fifth proportion of an alcohol-terminated dendrimer 151 exhibiting
a functionality greater than five.
[0077] In a third implementation, the polymer composition 100 can
include: an isophorone diisocyanate poly(tetramethylene
ether)glycol as the polyisocyanate-terminated polyol 110; a mixture
of tetramethylxylene diisocyanate 123 and
12-fold-hydrogenated-methylene-diphenyl-diisocyanate 122 as the
additional polyisocyanate 120; diethyl toluene diamine 131 as the
curative 130; a linear polyester diol as the soft polymer chain
140; a dendritic polyester polyol exhibiting a functionality of
sixteen as the high functionality crosslinker 150. Thus, in this
implementation, the polymer composition 100 includes: a first
proportion of isophorone diisocyanate poly(tetramethylene ether)
glycol; a second proportion of additional polyisocyanates 120
including a first quantity of tetramethylxylene diisocyanate 123
and a second quantity of
12-fold-hydrogenated-methylene-diphenyl-diisocyanate 122; a third
proportion of diethyl toluene diamine 131; a fourth proportion of a
linear polyester diol; and a fifth proportion of a dendritic
polyester polyol exhibiting a functionality greater than
sixteen.
[0078] Various implementations of the polymer composition 100 can
contain different weight percentages of each of the aforementioned
components depending on the desired properties of both the
prepolymer form and polymerized form of the polymer composition
100. However, in implementations of the polymer composition 100 for
use as a protective film layer 102 or sponge layer 103 in an
foldable electronic display, the polymer composition 100 can
include: a first weight proportion of polyisocyanate-terminated
polyol 110 between 50% and 90%; a second weight proportion of
additional polyisocyanates 120 of up to 10%; a third weight
proportion of a curative 130/chain length extender between 2% and
25%; a fourth weight proportion of a soft polymer chain 140 of up
to 30%; and a fifth weight proportion of high functionality
crosslinker 150 of up to 5%. In implementations of the polymer
composition 100 that include the catalyst, the polymer composition
100 can include a sixth proportion of the catalyst of up to 2%. In
implementations of the polymer composition 100 that include
additives, the polymer composition 100 can include a seventh weight
proportion of additives of up to 3%. In implementations of the
polymer composition 100 that are colored, the polymer composition
100 can include an eighth proportion of nanoparticle pigment and/or
organic colored dyes between 1% and 15% by weight. In another
implementation, the polymer composition 100 can include an eighth
proportion of particles of pigment and/or organic colored dyes
between 1% and 20% by weight (e.g., of the total weight of the
polymer composition 100). In this implementation, the eighth
proportion of particles of pigment can include particles exhibiting
sizes within a range of 5 nanometers to 500 nanometers.
[0079] In one implementation, the polymer composition 100 includes:
fifty-five percent to eighty percent of the first proportion of
polyisocyanate-terminated polyol 110 by weight; one percent to ten
percent of the second proportion of additional polyisocyanate 120
by weight; one percent to ten percent of the third proportion of
the curative 130 by weight; fifteen percent to thirty percent of
the fourth proportion of the soft polymer chain 140 by weight; and
zero to five percent of the fifth proportion of the high
functionality crosslinker 150 by weight. Further, the polymer
composition 100 can include up to one percent of a sixth proportion
of a catalyst (e.g., dibutyltin dilaurate) by weight.
[0080] The polymer composition 100 is a polyurethane-polyurea
polymer composition including the aforementioned components which
polymerize to form crosslinked hard polymer segments and soft
polymer segments via a first number of urethane linkages 104 and a
second number of urea linkages 106. The urethane linkages connect
(i.e. chemically bond): the polyol chains 116 of the polyisocyanate
terminated polyol no to the polyisocyanate terminations 114 of the
polyisocyanate terminated polyol 110; the soft polymer chain 140 to
the polyisocyanate terminations 114 and the additional
polyisocyanates 120; and the high functionality crosslinker to the
polyisocyanate terminations 114 and the additional polyisocyanates
120. The urea linkages 106 connect the curative 130 to the
polyisocyanate terminations 114 and the additional polyisocyanates
120.
[0081] Thus, polyurethane groups link soft polymer segments
(including the polyisocyanate terminated polyol no, the soft
polymer chain 140, and the additional polyisocyanates 120) within
the polymer composition 100 and crosslink (e.g., via the high
functionality crosslinker) the soft polymer segments with the hard
polymer segments while polyurea groups link the hard polymer
segments (including the curative 130, the additional
polyisocyanates 120, and the polyisocyanate terminations) within
the polymer composition 100. The copolymerization of these multiple
forms of soft polymer segments in the polymer composition 100
prevents the polymer composition 100 from hardening at lower
temperatures while the inclusion of the hard polymer segments in
the polymer composition 100 maintains the rigidity of the polymer
composition 100 at higher temperatures.
[0082] More specifically, the polymer composition 100 can include a
tuned ratio of urethane linkages 104 to urea linkages 106. The
urethane linkages 104 in the polymer composition 100 connect a
first quantity of polyether polyol 116 segments to a second
quantity of aliphatic diisocyanate terminations 114; connect a
third quantity of polyester polyol 141 segments to the second
quantity of the aliphatic diisocyanate terminations 114 and a
fourth quantity of additional diisocyanates 120; and connect a
fifth quantity of a high functionality crosslinker 150 to the
second quantity of the aliphatic diisocyanate terminations 114 and
the fourth quantity of additional diisocyanates 120. The urea
linkages 106 in the polymer composition 100 connect a sixth
quantity of an aromatic polyamine curative 131 to the second
quantity of the aliphatic diisocyanate terminations 114 and the
fourth quantity of additional diisocyanates 120.
[0083] The polymer composition 100 is configured to include both
urethane linkages 104 and urea linkages 106 in order to achieve the
desired mechanical properties (e.g., storage modulus, tensile
modulus, bendability) and optical clarity (e.g., optical
transmission, void size and fraction). Thus, the polymer
composition 100 can also define a ratio of urethane linkages 104 to
urea linkages 106 that yields these desired properties. For
example, the polymer composition 100 can define a molar ratio of
urethane linkages 104 to urea linkages 106 between two-to-five and
six-to-five.
[0084] However, the polymer composition 100 can also include
additional components or modified proportions of the above
components that may improve the properties of the polymer
composition 100 when applied as a protective layer in a foldable
electronic display.
6.1 Polyisocyanate-Terminated Polyol
[0085] The polymer composition 100 includes a first proportion of
polyisocyanate-terminated polyol 110 (e.g., a polyester,
polycaprolactone, polyether, polyacrylate, or polycarbonate) as the
largest weight proportion of the polymer composition 100. For
example, the polymer composition 100 can include between fifty-five
percent and eighty percent of the first proportion of
polyisocyanate-terminated polyol 110 by weight. The
polyisocyanate-terminated polyol 110 includes two subcomponents in
each prepolymer chain: the polyisocyanate-terminations 114 and the
polyol chain 116. The polyisocyanate-terminations 114 function as a
component in hard polymer segments of the polymer composition 100,
when reacted with the curative 130, the soft polymer chain 140,
and/or the high functionality crosslinker 150, while the polyol
chain ii6 functions as a soft linkage between the hard segments.
When reacted, the polyisocyanate-terminations and the polyol chain
116 bond to form urethane linkages. In one implementation, the
polyisocyanate-terminated polyol no includes a
diisocyanate-terminated polyether polyol with an average molecular
weight between 650 and 2600 g/mol. In a second implementation, the
polyisocyanate-terminated polyol no includes a
diisocyanate-terminated polyester polyol with an average molecular
weight between 500 and 2600 g/mol. Thus, the
polyisocyanate-terminated polyol no provides the chemical backbone
of the polymer composition 100.
[0086] The polymer composition 100 can include different quantities
of different average molecular weight of the polyol chain 116 in
the first proportion of the polyisocyanate-terminated polyol 110.
In one implementation, the polymer composition 100 includes a first
proportion of a polyisocyanate-terminated polyol no including: a
first quantity of the polyol chain 116 exhibiting a first average
molecular weight; and a second quantity of the polyol chain 116
exhibiting a second average molecular weight. Further, based on the
first quantity of the polyol chain 116 and the second quantity of
the polyol chain 116, the polymer composition 100 can exhibit a low
temperature storage modulus between 300 MPa and 1400 MPa and a high
temperature storage modulus between 10 MPa and 100 MPa.
[0087] In one implementation, the polymer composition 100 exhibits
properties of a copolymer including both lower average molecular
weight polyols (e.g., 650 g/mol) and higher average molecular
weight polyols (e.g., 2,000 g/mol) by including blends of the
polyisocyanate-terminated polyol 110 including polyol chains 116
with a range of molecular weights. For example, the polymer
composition 100 can include a first proportion of
aliphatic-diisocyanate-terminated polyol 111 including: a first
quantity of polyol chain 116 exhibiting an average molecular weight
of 650 g/mol; a second quantity of polyol chain 116 exhibiting an
average molecular weight of 1,000 g/mol; and a third quantity of
polyol chain 116 exhibiting an average molecular weight of 2,000
g/mol. Thus, by including varying average molecular weights, the
polymer composition 100 can exhibit properties of both lower
average molecular weight and higher average molecular weight
polyols.
[0088] The average molecular weight of the first proportion of
polyisocyanate-terminated polyol 110 may be increased to lower the
low temperature storage modulus of the polymer composition 100. For
example, the polymer composition 100 can include: a first
proportion of an aliphatic-diisocyanate-terminated polyol 111
including a first quantity of the polyol chain 116 characterized by
an average molecular weight of 650 g/mol, the first quantity
defining between ninety percent and one-hundred percent of the
first proportion by weight. The polymer composition 100 can
exhibit: a low temperature storage modulus between 900 MPa and 1400
MPa; and a high temperature storage modulus between 20 MPa and 30
MPa. Alternatively, in another example, the polymer composition 100
can include a first proportion of an
aliphatic-diisocyanate-terminated polyol 111: including a first
quantity of the polyol chain 116 characterized by an average
molecular weight of 650 g/mol, the first quantity defining between
sixty percent and eighty percent of the first proportion by weight;
and a second quantity of the polyol chain 116 characterized by an
average molecular weight of 2000 g/mol, the second quantity
defining between twenty percent and forty percent of the first
proportion by weight. In this example, the polymer composition 100
can exhibit: a low temperature storage modulus between 500 MPa and
800 MPa; and a high temperature storage modulus between 15 MPa and
25 MPa. Thus, the low temperature modulus of the polymer
composition 100 may be lowered by increasing the average molecular
weight of the polyisocyanate-terminated polyol 110.
[0089] The polymer composition 100 can include a
polyisocyanate-terminated polyol 110 with
polyisocyanate-terminations with an overall functionality equal to
or greater than two, where polyisocyanate-terminations with greater
functionality increase the storage modulus of the polymer
composition 100 by increasing the degree of crosslinking. In one
implementation, the polymer composition 100 includes a
diisocyanate-terminated polyol exhibiting an overall functionality
of two, thus reducing the storage modulus of the polymer
composition 100 at lower temperatures (e.g., -20.degree. C.) when
compared to polyisocyanates exhibiting higher overall functionality
(e.g., greater than two). For example, the polymer composition 100
can: include a diisocyanate-terminated polyol exhibiting an overall
functionality of two and including a polyol chain 116 bonded with a
first diisocyanate on a first end and bonded with a second
diisocyanate on a second end. The functional group of the
diisocyanate terminations not bound to the polyol chain 116 can
additionally bond to one of a curative 130, a soft polymer chain
140, or a high functionality crosslinker 150. In this
implementation, the polymer composition 100 exhibits a low
temperature storage modulus between 300 MPa and 1000 MPa.
[0090] Additionally, the polymer composition 100 can include a
polyisocyanate-terminated polyol 110 with either aromatic or
aliphatic polyisocyanate 120-terminations (or a blend thereof)
depending on the desired characteristics of the polymer composition
100, wherein polyisocyanate-terminated polyol 110 including
aromatic terminations are generally characterized by improved
impact and scratch resistance and high-temperature bend
performance, while polyisocyanate-terminated polyols no including
aliphatic terminations are generally characterized by improved
optical clarity, low-temperature bend performance, and longer
pot-life. In one implementation, the polymer composition 100
includes a proportion of aromatic polyisocyanate-terminated polyol
110 and a proportion of aliphatic polyisocyanate-terminated polyol
110 to achieve more balanced characteristics representative of both
aromatic and aliphatic-polyisocyanate terminations 114. In one
implementation, as shown in FIG. 2, the polymer composition 100
includes a polyisocyanate-terminated polyol 110 terminated by
12-fold hydrogenated methylene diphenyl diisocyanate (hereinafter
"H12 MDI"), which is an aliphatic diisocyanate. In alternative
implementations, the polyisocyanate-terminated polyol 110 can
include other isocyanate terminations 114, such as isophorone
diisocyanate (hereinafter "IPDI") and/or hexamethylene diisocyanate
(hereinafter "HDI").
[0091] The polyisocyanate-terminated polyol 110 can include a
variety of polyol chains 116 common in various foldable
polyurethanes, such as polyether polyols, polyester polyols,
polycaprolactone polyols, polyacrylic polyols, and polycarbonate
polyols. In one implementation, the polyisocyanate-terminated
polyol 110 includes poly(tetramethylene ether) glycol (hereinafter
"PTMEG") as the polyol chain 116.
[0092] In one implementation, as shown in FIG. 2, the polymer
composition 100 includes H12 MDI terminated PTMEG as the
polyisocyanate-terminated polyol 110. In a second implementation,
the polymer composition 100 includes H12 MDI terminated
polybutylene adipate (polyester) as the polyisocyanate terminated
polyol.
[0093] In one variation, the first proportion of
polyisocyanate-terminated polyol 110 further includes polyol chains
116 terminated by a first set of diisocyanates; and a second set of
diisocyanates (e.g., additional isocyanates 120) configured to
promote polymerization of the third proportion of the curative 130,
the fourth proportion of soft polymer chains 140, and the fifth
proportion of the high functionality crosslinker 150. For example,
the polymer composition 100 can include the first proportion of
aliphatic-diisocyanate-terminated polyol in including polyol chains
116 terminated by a first set of aliphatic diisocyanates and a
second set of aliphatic diisocyanates configured to promote
polymerization of the third proportion of the curative 130, the
fourth proportion of the soft polymer chains 140, and the fifth
proportion of the high functionality crosslinker; and exhibiting a
molar ratio of the first set of diisocyanates to the second set of
diisocyanates between two and four. In this example, the second set
of aliphatic diisocyanates perform a similar function (e.g.,
promote polymerization between soft segments and/or hard segments)
to the second proportion of the aliphatic polyisocyanate 120, as
described below.
6.2 Additional Polyisocyanates
[0094] The polymer composition 100 includes a second proportion of
additional polyisocyanates 120 configured to increase mechanical
strength and rigidity of the polymer composition 100. More
specifically, the polymer composition 100 includes a second
proportion of additional polyisocyanates 120 (i.e. polyisocyanates
that do not terminate polyol chains as described above) and can
include a quantity of aliphatic polyisocyanates or a mixture of a
quantity of aliphatic polyisocyanates and a quantity of aromatic
polyisocyanates. The inclusion of the additional polyisocyanates
120 functions to further modify the hard polymer segments and soft
polymer chains 140 to achieve specific material property targets,
such as increased scratch and/or impact resistance (in
implementations of the polymer composition 100 including the
additional polyisocyanates includes aromatic isocyanates).
Furthermore, the incorporation of sterically hindered urethane
groups in the additional polyisocyanates 120 improves
processability by reducing side reactions with water in the
prepolymer mixture and enabling well-controlled reactions between
the prepolymer mixture and hydroxyl and/or amine groups. The
polymer composition 100 can include between one and ten percent of
the aliphatic isocyanate by weight.
[0095] Like the polyisocyanate-terminated polyol 110, the
additional polyisocyanates 120 can exhibit an overall functionality
equal to or greater than two, wherein additional polyisocyanates
120 with greater functionality increase the storage modulus of the
polymer composition 100 by increasing the degree of crosslinking.
In one implementation, the polymer composition 100 includes an
aliphatic diisocyanate as the additional polyisocyanate 120.
[0096] In one implementation, the polymer composition 100 can
include H12 MDI, as the additional isocyanates 120, as the H12 MDI
increases the storage modulus of the polymer composition 100 at
high temperatures without substantially increasing the storage
modulus at low temperatures. For example, the polymer composition
100 can include a second proportion of H12 MDI defining between two
percent and twenty percent of a mixture of the first proportion and
the second proportion by weight. In this example, the polymer
composition 100 can include the second proportion of H12 MDI
exhibiting a functionality of two and configured to polymerize with
the third proportion of the curative 130/chain length extender, the
fourth proportion of the soft polymer chain 140, and/or fifth
proportion of the high functionality crosslinker 150. Therefore, in
this implementation, the polymer composition 100 can include both a
first proportion of H12 MDI terminated polyol including H12 MDI
terminations, and a second proportion of H12 MDI as the additional
polyisocyanates 120.
[0097] In another implementation, polymer composition 100 can
include IPDI as the additional polyisocyanates 120, as IPDI can
increase the tensile and storage modulus of the polymer composition
100 without substantially increasing the storage modulus at low
temperatures. Furthermore, IPDI reduces the viscosity of the
prepolymer mixture compared to prepolymer mixtures containing H12
MDI.
[0098] In another implementation, as shown in FIG. 2, the polymer
composition 100 can include a quantity of tetramethylxylene
diisocyanate (hereinafter "TMXDI"), as the TMXDI has a low
reactivity when compared to aliphatic polyisocyanates such as H12
MDI, and imparts UV stability to the polymer composition 100.
Additionally, TMXDI increases the storage modulus of the polymer
composition 100 at high temperatures without substantially
increasing the storage modulus at low temperatures by improving the
stiffness of hard segments in the polymer composition 100.
Furthermore, TMXDI reduces the viscosity of the prepolymer mixture
more effectively than other common aliphatic polyisocyanates and
prevents discoloration of the polymer composition 100 (e.g.,
yellowing of the protective film layer 102).
[0099] In yet another implementation, the polymer composition 100
includes both TMXDI and excess H12 MDI (i.e. H12 MDI that does not
terminate the polyisocyanate-terminated polyol 110) providing a
mixture of the abovementioned properties of the polymer composition
100 when including TMXDI and H12 MDI separately. For example, the
polymer composition 100 can include a second proportion of
aliphatic polyisocyanate 120 including a mixture of TMXDI and H12
MDI, the second proportion configured to: increase the tensile and
storage modulus of the polymer composition 100 without
substantially increasing the storage modulus at low temperatures;
impart UV stability to the polymer composition 100; and reduce the
viscosity of the prepolymer mixture. In this implementation, the
polymer composition 100 can include between zero percent and
fifteen percent additional H12 MDI by weight and between zero and
ten percent TMXDI by weight. The polymer composition 100 can
include the second proportion of aliphatic isocyanate defining a
molar ratio of excess H12 MDI to TMXDI between 0.8 and 2.0. For
example, the polymer composition 100 can include the second
proportion of aliphatic isocyanate defining a molar ratio of excess
H12 MDI to TMXDI of one.
6.3 Curative and Chain Length Extender
[0100] The polymer composition 100 includes a third proportion of
the curative 130/chain length extender. The curative 130 functions
to extend the chain length of hard segments, which include the
polyisocyanate terminations 114 of the polyisocyanate-terminated
polyols 110 and the aliphatic polyisocyanate 120, by binding with
polyisocyanate terminations 114 via polyurethane bonds and polyurea
bonds. Thus, the inclusion of greater proportions of the curative
130 relative to the soft polymer chain 140 of the polymer
composition 100 increases the storage modulus of the polymer
composition 100.
[0101] In one example, the polymer composition 100 can: include a
third proportion of the curative 130 defining eleven percent of the
polymer composition 100 by weight; and include a fourth proportion
of the soft polymer chain 140 defining eighteen percent of the
polymer composition 100 by weight. In this example, the polymer
composition 100 exhibits a low temperature storage modulus between
700 MPa and 1400 MPa at -20 degrees Celsius; a high temperature
storage modulus between 15 MPa and 40 MPa at 85 degrees Celsius;
and a room temperature storage modulus between 50 MPa and 400 MPa
at 20 degrees Celsius.
[0102] In another example, the polymer composition 100 can: include
a third proportion of the curative 130 defining eight percent of
the polymer composition 100 by weight; and include a fourth
proportion of the soft polymer chain 140 defining twenty-five
percent of the polymer composition 100 by weight. In this example,
the polymer composition 100 exhibits a low temperature storage
modulus between 500 MPa and 800 MPa at -20 degrees Celsius; and a
high temperature storage modulus between 20 MPa and 30 MPa at 85
degrees Celsius. Therefore, the polymer composition 100 can exhibit
a varying range of low temperature and high temperature storage
modulus based on the ratio of the curative 130 to the soft polymer
chain 140 included in the polymer composition 100.
[0103] In yet another example, the polymer composition 100 includes
the third proportion of the curative 130 defining between zero
percent and ten percent of the polymer composition 100 by weight
and exhibits a high temperature storage modulus between 15 MPa and
35 MPa at 85 degrees Celsius. More specifically, where the polymer
composition 100 includes a lower weight percent of the curative 130
between zero percent and five percent, the polymer composition 100
exhibits a high temperature storage modulus between 15 MPa and 25
MPa at 85 degrees Celsius. Alternatively, where the polymer
composition 100 includes between five percent and ten percent of
the curative 130 by weight, the polymer composition 100 exhibits a
high temperature storage modulus between 25 MPa and 35 MPa at 85
degrees Celsius.
[0104] The polymer composition 100 can include a curative 130 with
a low molecular weight (e.g., less than 200 g/mol) configured to
increase the number of urethane and/or urea groups per unit length
of the polymer composition 100. For example, the polymer
composition 100 can include curatives/chain length extenders such
as 1,4 butanediol (e.g., with an average molecular weight of 98.12
g/mol), 2-methyl-1,3-propanediol, diethylene glycol,
1,5-pentanediol, or 1,6 hexanediol.
[0105] In one implementation, as shown in FIG. 2, the polymer
composition 100 includes a polyamine curative such that hard
segments of the polymer composition 100 include a polyurea chain,
thus increasing the number of polyurea groups present in the
polymer composition 100. Furthermore, the polymer composition 100
can include a diamine curative to promote the polymerization of
linear polyurea segments 106 when compared to higher functional
polyamine curatives. For example, the polymer composition 100 can
include: a first proportion of H12 MDI terminated PTMEG; a second
proportion of additional polyisocyanates (e.g., H12 MDI or H12 MDI
and TMXDI); a third proportion of a diamine curative including an
aromatic ring and two amine functional groups located opposite each
other on the aromatic ring. The polymer composition 100 can be
configured such that each amine functional group of the second
proportion of the diamine curative forms a polyurea bond with a
diisocyanate group of the first proportion of H12 MDI terminated
PTMEG and/or with aliphatic isocyanates of the second
proportion.
[0106] The polymer composition 100 can also include aromatic
curatives, such as aromatic polyamine curatives or aromatic
hydroxy-functional curatives, where aromatic polyamine curatives
contribute polyurea bond structures to the polymer composition 100
and aromatic hydroxy-functional curatives contribute polyurethane
bond structures. In one implementation, the polymer composition 100
includes one or more isomers of diethyl toluene diamine
(hereinafter "DETDA") as the curative 130, such as
3,5-diethyltoluene-2,4-diamine; 3,5-diethyltoluene-2,6-diamine; or
a mixture of both. In this implementation, the polymer composition
100 can include a proportion of the curative 130 further including
a mixture of approximately 80% 3,5-diethyltoluene-2,4-diamine and
approximately 20% 3,5-diethyltoluene-2,6-diamine. Implementations
of the polymer composition 100 including DETDA exhibit a high
degree of crystallinity and improved high temperature properties
when compared to other curatives. In one implementation, the
polymer composition 100 includes an isomer of DEDTA (e.g., Ethacure
100) with an average molecular weight of 178.28 g/mol and defining
between seven percent and ten percent of the polymer composition
100 by weight. In this example, the polymer composition 100 can
exhibit a storage modulus greater than 20 MPa at 85 degrees
Celsius.
[0107] In another implementation, the polymer composition 100
includes hydroquinone bis(2-hydroxyethyl)ether, ethoxylated
hydroquinone bis(2-hydroxyethyl)ether or mixtures thereof to enable
well-controlled reactions between the prepolymer mixture and
curative when compared to compositions including DETDA.
6.4 Soft Polymer Chain
[0108] The polymer composition 100 includes a fourth proportion of
a soft polymer chain 140 to prevent excess hardening of the polymer
composition 100 at low temperatures. The properties of the soft
polymer chain 140, such as its weight percentage within the polymer
composition 100, molecular weight, and chemical backbone type of
the soft polymer chain 140 can contribute to the storage modulus
characteristics of the polymer composition 100. In particular, the
molecular weight and composition of the soft polymer chain 140
significantly impact the low temperature storage modulus (e.g., the
storage modulus at or below 20 degrees Celsius) of the polymer
composition 100. Furthermore, in one implementation, a mixture of
soft polymer chain 140 backbone chemistries is utilized to control
the extent of crystallization of the soft polymer chains 140 at low
temperatures and thus control the flexibility of the polymer
composition 100 at low temperatures. In one implementation, the
polymer composition 100 includes between fifteen percent and thirty
percent of the fourth proportion of the soft polymer chain 140 by
weight.
[0109] The polymer composition 100 can include a secondary polyol
as the soft polymer chain 140 that is configured to control
crystallization of the polyol chains 116 of the
polyisocyanate-terminated polyol no by intermixing with the polymer
chains of the chain extended polyisocyanate-terminated polyol 110.
Thus, the soft polymer chain 140 can reduce the storage modulus of
the polymer composition 100 at low temperatures without
substantially reducing the storage modulus at high temperatures
because crystallization of the polyol chains 116 does not occur at
high temperatures. For example, the polymer composition 100 can
include a fourth proportion of the soft polymer chain 140 defining
twenty weight percent of the polymer composition 100. The polymer
composition 100 can exhibit a low temperature storage modulus
between 800 MPa and 1400 MPa at -20 degrees Celsius and a high
temperature storage modulus between 20 MPa and 40 MPa at 85 degrees
Celsius. Alternatively, in another example, the polymer composition
100 can include a fourth proportion of the soft polymer chain 140
defining thirty weight percent of the polymer composition 100. The
polymer composition 100 can exhibit a low temperature storage
modulus between 500 MPa and 800 MPa at -20 degrees Celsius and a
high temperature storage modulus between 20 MPa and 40 MPa at 85
degrees Celsius.
[0110] In one implementation, as shown in FIG. 2, the polymer
composition 100 includes a polyester polyol 141 as the soft polymer
chain 140, which can further improve the chemical stability of the
polymer composition 100. In a second implementation, the polymer
composition 100 includes a polycaprolactone polyol diol with an
average molecular weight between 330 and 1000 g/mol as the soft
polymer chain 140, which can increase wear resistance, gloss, and
UV resistance in addition to decreasing the low temperature storage
modulus of the polymer composition 100. Alternatively, the polymer
composition 100 can include other linear polyester diols with an
average molecular weight between 500 and 2000 g/mol.
6.5 High Functionality Crosslinker
[0111] The polymer composition 100 includes a fifth proportion of
the high functionality crosslinker 150. The high functionality
crosslinker 150 functions to increase the crosslinking density of
the polymer composition 100, thereby improving the high temperature
storage modulus of the polymer composition 100. The polymer
composition 100 can include a high functionality crosslinker 150
characterized by functionalities between three and one hundred
depending on the desired high temperature shear modulus. For
example, the polymer composition 100 can include a first high
functionality crosslinker 150 characterized by a functionality of
five and exhibiting a high temperature storage modulus between 15
MPa and 30 MPa at 85 degrees Celsius. Alternatively, the polymer
composition 100 can include a second high functionality crosslinker
150 characterized by a functionality of twenty and exhibiting a
high temperature storage modulus between 25 MPa and 40 MPa at 85
degrees Celsius.
[0112] In one implementation, as shown in FIG. 2, the polymer
composition 100 includes a dendritic polyester polyol as the high
functionality crosslinker 150, which, in comparison to a low
functionality crosslinker, results in higher crosslinking density
in the polymer composition 100 for a given weight proportion of
crosslinker. Furthermore, the dendritic polyester polyol encourages
spatially heterogeneous crosslinking within the soft polymer chain
140 when compared to a low functionality crosslinker used to
achieve the same overall bulk crosslink density. The spatially
heterogenous crosslinks may improve the low-temperature flexibility
of the polymer composition 100 by providing a relatively wider
distribution of average molecular weight between crosslinks in the
polymer composition 100 when compared to lower functionality
crosslinkers. In one implementation, the polymer composition 100
includes a dendritic polyester polyol with a functionality of
twenty-three as the high functionality crosslinker 150. In a second
implementation, the polymer composition 100 includes a dendritic
polyester polyol with a functionality of sixteen as the high
functionality crosslinker 150. In a third implementation, the
polymer composition 100 includes a dendritic polyester polyol with
a functionality of six as the high functionality crosslinker
150.
6.6 Catalyst
[0113] The polymer composition 100 can also include a sixth
proportion of a catalyst. The catalyst functions to promote (during
polymerization of the polymer composition 100) polyol-isocyanate
and/or amine-isocyanate reactions in order to balance the pot-life
and reactivity of the prepolymer mixture for a roll-to-roll
manufacturing process. Thus, the polymer composition 100 can
include any catalyst that promotes urethane and/or urea reactions.
In one implementation, the polymer composition 100 includes
tetravalent diorganotins, such as dibutyltin dilaurate (hereinafter
"DBTDL"), as the catalyst. In a second implementation, the polymer
composition 100 includes organozincs, such as zinc neodecanoate, as
the catalyst. In a third implementation, the polymer composition
100 includes blends of zinc and bismuth catalysts, such as zinc and
bismuth carboxylate, as the catalyst.
6.7 Surface Additive
[0114] The polymer composition 100 can also include a seventh
proportion of a surface additive. The surface additive functions to
reduce the surface tension of the prepolymer mixture of the polymer
composition 100, thereby improving the surface quality of the cured
film of polymer composition 100. In one implementation, the polymer
composition 100 includes a silicone oil surface additive such that
the surface additive can be added to the prepolymer mixture of the
polymer composition 100 independent on the specific solvents
included in the prepolymer mixture of the polymer composition 100.
In a second implementation, the polymer composition 100 includes
polyether-modified polydimethylsiloxane, which can prevent
cratering and increase gloss in a thin film of the polymer
composition 100. Additional examples of surface additives include,
but are not limited to, wetting agents, de-foamers, surfactants,
etc.
6.8 Prepolymer Solvents
[0115] The prepolymer form of the polymer composition 100 can
include a solvent at between 20% and 80% weight proportion of the
prepolymer mixture depending on the manufacturing method and
desired drying properties of the prepolymer mixture. The prepolymer
form of the polymer composition 100 can include a solvent or
combination of solvents in which the prepolymer form of the polymer
composition 100 exhibits sufficient solubility, such as a ketone
solvent. More specifically the prepolymer form of the polymer
composition 100 can include methyl isobutyl ketone (MIBK),
cyclohexanone, acetone, and/or MEK. The prepolymer form of the
polymer composition 100 can include an aprotic, polar organic
solvent, in order to reduce the viscosity of the prepolymer form of
the polymer composition 100. In one implementation, the solvent can
also contain smaller proportions of toluene and/or cyclohexanone to
improve coating quality during the drying process.
[0116] Furthermore, in some manufacturing processes, the prepolymer
form of the polymer composition 100 can include multiple component
mixtures each with a different solvent and/or solvent proportions.
For example, the prepolymer form of the polymer composition 100 can
include a first mixture including the catalyst, the curative
130/chain extender, the soft polymer chain 140, surface additives,
and the high functionality crosslinker 150, and a second mixture
including the polyisocyanate-terminated polyol no and the aliphatic
isocyanate 120. In this example, each of the two mixtures can
include a different solvent.
7. Manufacturing
[0117] The polymer composition 100 can be manufactured via a
continuous roll-to-roll process, described in further detail in
U.S. patent application Ser. No. 15/895,971, that produces a thin
layer exhibiting both chemical and physical cross-linking to yield
clear optical properties and particular mechanical properties, such
as resistance to impact, pencil hardness, etc.
[0118] The polymer composition 100 can be manufactured via a
roll-to-roll manufacturing process including: mixing a first
solution and a second solution to define a viscous material, the
first solution including a first proportion of a
polyisocyanate-terminated polyol 110, a second proportion of an
aliphatic polyisocyanate 120, and a seventh proportion of the
solvent, the second solution including a third proportion of a
curative 130, a fourth proportion of a soft polymer chain 140, a
fifth proportion of a high functionality crosslinker 150, and a
sixth proportion of a catalyst; advancing a substrate from a first
roll across a surface continuously at a first speed; depositing the
first viscous material characterized by a first viscosity through a
deposition head onto the substrate, the first viscous material
flowing laterally across the substrate to form a thin layer of
substantially uniform thickness over the substrate over a period of
time while the substrate advances along the surface; heating the
thin layer to remove solvent from the thin layer and to induce
reaction between the prepolymer, the aliphatic polyisocyanate, the
curative, the soft polymer chain, and the cross-linking agent and
to cure the thin layer via physically and chemically cross-linked
polymer chains.
[0119] In one implementation, the polymer composition 100 can be
manufactured by mixing a first solution and a second solution
before combining the first solution and the second solution. The
first solution includes: twenty percent to eighty percent of the
first proportion of aliphatic-diisocyanate-terminated polyol 111
and the second proportion of additional diisocyanates 121 by
weight; and up to eighty percent of a first solvent by weight. The
first solution can include between fifty percent to eighty percent
of the total solid content of the polymer composition 100 by weight
while the second solution can include twenty to fifty percent of
the total solid content of the polymer composition 100 by weight.
The second solution includes: twenty percent to eighty percent of
the third proportion of an aromatic diamine curative 131, the
fourth proportion of a polyester polyol 141, and the fifth
proportion of a high functionality dendrimer 151; and up to eighty
percent of a second solvent (which may be the same solvent as the
first solvent or a different solvent). The polymer composition 100
can then be manufactured by combining the first solution and the
second solution via a roll-to-roll manufacturing process (e.g., as
described above) at a ratio between one-to-one and four-to-one by
weight. Additionally, the polymer composition 100 can be
manufactured by adding a sixth proportion of a catalyst (e.g.,
dibutyltin dilaurate) to the second solution before combining first
solution and the second solution, the sixth proportion defining
between zero percent and two percent of the polymer composition 100
by weight. For example, a first proportion of H12MDI terminated
PTMEG as the aliphatic-polyisocyanate-terminated polyol 111 and a
mixture of H12MDI and TMXDI as the second proportion of additional
diisocyanates 121 can be mixed to form a first solution. The H12
MDI forms a defined hard segment in the final polymer composition
100, thus increasing the strength and high temperature storage
modulus of the final polymer composition 100, while the PTMEG
improves the elastomeric properties of the polymer composition 100.
The TMXDI forms a hard segment, thus increasing the strength and
rigidity of the polymer composition 100, while preventing color
changes (e.g., preventing the protective film layer 102 from
turning yellow). Separately, diethyltoluene diamine as the aromatic
diamine curative 131, polycaprolactone diol as the polyester polyol
141, and an alcohol dendrimer as the high functionality dendrimer
151 can be mixed to form a second solution. The diethyltoluene
diamine forms a well-defined hard segment in the final polymer
composition 100, thus increasing strength of the polymer
composition 100 at both low temperatures and high temperatures. The
polycaprolactone diol disrupts the soft segment (e.g., PTMEG
chains) morphology and lowers the low temperature storage modulus,
thus counteracting the increase in low temperature storage modulus
caused by the inclusion of TMXDI and diethyltoluene diamine. The
alcohol dendrimer, when reacted with other components, forms a
highly crosslinked polymer exhibiting large distances between
cross-links, which enables the polymer composition 100 to remain
relatively ductile at low temperatures and stable at high
temperatures. The polymer composition 100 can be manufacture by
mixing the first solution and the second solution via a
roll-to-roll process, thus forming the polymer composition 100. The
synergistic effects of each of these components enables the polymer
composition 100 to exhibit increases in storage modulus at high
temperatures and decreases in storage modulus at low temperatures,
each independently of the other.
[0120] As a person skilled in the art will recognize from the
previous detailed description and from the figures and claims,
modifications and changes can be made to the embodiments of the
invention without departing from the scope of this invention as
defined in the following claims.
* * * * *